A new blog entry from @rikesh.shah gives guidance on use of TfL’s intellectual property in your apps:

TfL’s open data policy helps to bring in more customer innovation created by you through unique product features and design. Building on the design point, unless otherwise agreed with TfL, a condition of our open data usage (we have very few conditions) is that your app shouldn’t be using TfL’s registered trademarks or other intellectual property.

For several reasons, your app shouldn’t be suggesting it’s produced or endorsed by TfL in any way. There are a few instances where app icons, landing pages and embedded symbols use TfL’s registered trademarks, for example the TfL roundel mark and the words ‘Oyster’ or ‘TfL’.